In general, in a motorized two-wheeled vehicle of the type having a vehicle body provided with an internal combustion engine and a blower for forcibly cooling the engine, a disadvantage arises in that, especially when the vehicle is driven at low speed or is stopped, warm air obtained after cooling is not diffused and directly affects the driver, the carburetor and other structure which is positioned therebehind. This leads to discomfort for the driver while the carburetor is brought to a poor operating condition.